1. Field of the Invention
The present invention relates to an inspecting apparatus for a foreign matter for optically detecting a foreign matter got entered an object being inspected, namely, a light-transmitting container, such as a bottle and a PET bottle, filled with a liquid product, such as liquid agents and drinks, and to an inspecting mechanism thereof, and more particularly to an inspecting apparatus for a foreign matter for detecting in real time a foreign matter got entered a container placed on an inspection table that rotates at a high speed in sync with a transportation speed of the container on production line and to an inspecting mechanism thereof.
2. Description of the Related Art
Adoption of the HACCP (Hazard Analysis Critical Control Point) system, which is highly evaluated across the world as a sanitary control system method, to the Food Sanitation Law and enforcement of the PL (Product Liability) Law in recent years have been making it mandatory to further ensure the product safety by forestalling a hazard, such as microbial contamination and entrance of foreign matters of other kinds, that could occur in any stage from manufacturing/processing of products, such as food and drugs, to consumption by end consumers through storage/distribution of the products.
Conventionally, in a production line of a manufacturing/processing factory for manufacturing liquid products (liquid agents, drinks, etc.), microbial contamination is prevented by sterilization with heating, and entrance of a foreign matter is prevented by removing the foreign matter with a cyclone separator. After the liquid product is filled in a container, such as a can and a bottle, final inspection is conducted by exploiting transmission or reflection of light. More specifically, when an object being inspected is a transparent container filled with a liquid, such as liquid agents and drinks, the object being inspected is pictured by a CCD camera, and digital image data thus obtained is processed by an image processing apparatus. Then, the presence or absence of a foreign matter got entered the liquid inside the container and the presence or absence of a flaw of the container are detected, whereby the conformity of the final product is automatically judged.
For example, as a method for detecting a foreign matter got entered a liquid agent or a drink inside a sealed container, such as an ampoule, there is known a foreign matter detecting method, by which a cylindrical container is rotated at a high speed (for example, at 6000 rpm approximately) in an upright posture and stopped after a foreign matter is forced upward, and the foreign matter falling downward is shot by a camera, so that the foreign matter is detected from the trail of movements. As has been described, in a case where the container is made of a light-transmitting member and is filled with a transparent (including translucent) liquid, it is possible to inspect the inside of the container by picturing the container with a CCD camera or the like and carrying out image processing even after the container is sealed.
Also, as an inspecting system for a deposited foreign matter inside the container, there is a system described in Japanese Patent Laid-Open No. 2001-201457 filed by the applicant of the present application. FIG. 5 is a plan view showing an arrangement of a major portion of an inspecting system for a foreign matter described in this publication. PET bottles filled with drinks, such as soft drinks and juice, on a production line are transported successively at regular intervals in a direction indicated by an arrow A of FIG. 5 on a linearly moving transportation conveyer 22 by rotations of a screw (worm gears) 21. An inspecting mechanism unit 30 for inspecting the PET bottles for a foreign matter is provided with an inspection table 31 including carrying in/carrying out star wheel boards 32 and 33 linked to the transportation conveyer 22 and a large-diameter star wheel board for use in inspection. Each PET bottle flowing into the inspecting mechanism unit 30 is transported by these transportation means along paths R1, R2, and R3 of FIG. 5. The inspecting mechanism unit 30 is arranged to inspect in real time the respective PET bottles being transported along the path R2 at a high speed (approximately 1200 bottles/min.) for foreign matters deposited inside.
According to the inspecting system described above, mount sections (inspection section) 31a, on which respective objects being inspected are sequentially mounted in an upright posture, are formed along the circumference of the inspection table 31 that is driven rotationally. Each of the mount sections 31a is formed from a filter made of a light-transmitting member, such as resin and glass. Each of the mount sections 31a is provided with restraining means for an object being inspected formed of a holding mechanism 34 as shown in FIG. 6, for example. A PET bottle 1 mounted on the mount section 31a is fixed thereto by being held with the holding mechanism 34 at the side face portions, and is transported along the path R2 of FIG. 5. FIG. 7 is a view showing an example of an arrangement as to the placement of illuminating means and imaging means to detect a deposited foreign matter. According to this example, first illuminating means 35 having a ring of light emitting portion is provided above the filter (the mount section) 31a, and a light emitting portion of second illuminating means 35 and a light receiving portion of imaging means 36 are provided under the filter 31a. Then, objects being inspected 1, which are held by the holding mechanisms 34 at either side of the side face or sandwiched by a belt or the like, are being transported successively in an upright posture along the annular path R2 of FIG. 5, whereby the containers are inspected successively for foreign matters inside based on image information from a plurality of inspection cameras 36.
Incidentally, as has been described, detecting a foreign matter by the trail of the foreign matter that is forced upward and then allowed to fall downward by rotating the object being inspected is known as a method for detecting a foreign matter in the liquid inside a sealed container. However, this method has a problem that detection is impossible when a foreign matter has too large specific gravity to be forced upward by rotations or a foreign matter is a suspended foreign matter that does not fall downward. Also, inspection takes too long with the method for detecting a foreign matter by observing the trail of the foreign matter falling downward based on pictured image data. Hence, this method may not be applicable to an inspecting system for products mass-produced at a high transportation speed.
On the contrary, the system described in Japanese Patent Laid-Open No. 2001-201457 is applicable as an inspecting system for products mass-produced at a high transportation speed, because it can successively inspect objects being inspected that are being transported at a high speed. However, this system is intended to chiefly detect a deposited foreign matter, and a suspended foreign matter that does not deposit has to be detected by another inspecting mechanism. Even if an imaging camera and a illuminating apparatus for detecting a suspended foreign matter are provided to inspect objects being inspected for both the deposited and suspended foreign matters by a single inspecting mechanism, when the entire side face of the object being inspected is pictured by the conventional inspecting mechanism, there arises a problem that a slot pitch portion of the wheel for fixing the object being inspected placed on the inspection star wheel or a portion of the holding mechanism blocks illuminating light, or such a portion comes into the field of view of the imaging camera. If the illuminating means and the imaging means are placed so as to avoid the slot pitch portion of the wheel or the portion of the holding mechanism, irregular reflection occurs due to an angle of incidence of the illuminating light on the object being inspected or the shape of the container, and such adverse effects make the detection of a foreign matter less accurate. Hence, it is difficult to inspect the object being inspected entirely by a single inspecting mechanism at high accuracy. Further, in the case of detecting a foreign matter in the liquid by illuminating the side face portion of the object being inspected placed on the inspection table by the illuminating means placed behind the object being inspected and picturing the side face region by the imaging means placed in front of the object being inspected, there is a blind spot in the illuminated region (or the pictured region) at the bottom portion of the side face of the object being inspected, which poses a problem that a foreign matter present within the blind spot cannot be detected.